1. Field of the Invention
The present invention provides a light source adjusting device, and more particularly, to a light source adjusting device for a projection system.
2. Descriptions of the Related Art
Due to advantages, such as a long service life, a short start-up period, a wide display color gamut and convenience in increasing the dynamic contrast, light emitting diodes (LEDs) are now widely used in many display products. Especially in the projector industry, the use of LEDs as a light source of a projector can not only decrease the operating temperature of the projector, but also effectively reduce the volume of the projector to result in better portability as compared to conventional projectors using UHP lamps as light sources. Therefore, projectors using LEDs have won wide popularity among consumers.
However, because light beams emitted by the LEDs are relatively divergent, LEDs have poorer performance in terms of luminance and light emitting efficiency than conventional UHP lamps when used in projectors. On the other hand, increasing the number of LEDs to improve the luminance of a projector would lead to an excessively large volume of the projector and complex arrangement of internal components thereof.
Additionally, technologies that utilize blue light LEDs or ultraviolet (UV) light to excite blue phosphors, red phosphors and green phosphors disposed on the color wheel to generate the three primary colors (i.e., blue, red and green) respectively have been disclosed in the prior art. However, because the color wheel used in these technologies is of a mechanically rotary structure, it tends to have a longer response time and is liable for failure after an extended time period of operation. Moreover, such technologies using blue LEDs or UV light to excite phosphors cannot substantially overcome the problems of low luminance and poor light emitting efficiency.
In view of this, an urgent need still exists in the art to improve the luminance of light sources of projectors by using a limited number of optical components and within a limited space so that the projection system can have a better luminance performance and higher light emitting efficiency.